diff --git a/project/Build.scala b/project/Build.scala
index be39358ff582..442ac3c2f4ff 100644
--- a/project/Build.scala
+++ b/project/Build.scala
@@ -81,7 +81,7 @@ object DottyBuild extends Build {
       val args = Def.spaceDelimited("<arg>").parsed
       val jars = Seq((packageBin in Compile).value.getAbsolutePath) ++
           getJarPaths(partestDeps.value, ivyPaths.value.ivyHome)
-      val dottyJars  = "-dottyJars " + jars.length + " " + jars.mkString(" ")
+      val dottyJars  = "-dottyJars " + (jars.length + 1) + " dotty.jar" + " " + jars.mkString(" ")
       // Provide the jars required on the classpath of run tests
       runTask(Test, "dotty.partest.DPConsoleRunner", dottyJars + " " + args.mkString(" "))
     },
@@ -118,8 +118,8 @@ object DottyBuild extends Build {
 
       ("-DpartestParentID=" + pid) :: tuning ::: agentOptions ::: travis_build ::: fullpath
     }
-  ) ++ addCommandAlias("partest", ";test:package;package;lockPartestFile;test:test;runPartestRunner") ++
-       addCommandAlias("partest-only", ";test:package;package;lockPartestFile;test:test-only dotc.tests;runPartestRunner")
+  ) ++ addCommandAlias("partest", ";test:package;package;test:runMain dotc.build;lockPartestFile;test:test;runPartestRunner") ++
+       addCommandAlias("partest-only", ";test:package;package;test:runMain dotc.build;lockPartestFile;test:test-only dotc.tests;runPartestRunner")
 
   lazy val dotty = Project(id = "dotty", base = file("."), settings = defaults)
 
diff --git a/scripts/jobs/validate/partest b/scripts/jobs/validate/partest
index ee45a39199e4..55ec9f4c1c94 100755
--- a/scripts/jobs/validate/partest
+++ b/scripts/jobs/validate/partest
@@ -4,5 +4,5 @@ baseDir=${WORKSPACE-`pwd`}
 scriptsDir="$baseDir/scripts"
 . $scriptsDir/common
 
-sbt $sbtArgs update compile "partest-only run --show-diff --verbose"
+sbt $sbtArgs update compile "partest-only --show-diff --verbose"
 
diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index bd03cc056e2a..65df55a9da2c 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -193,9 +193,11 @@ object Denotations {
      */
     def requiredSymbol(p: Symbol => Boolean, source: AbstractFile = null, generateStubs: Boolean = true)(implicit ctx: Context): Symbol =
       disambiguate(p) match {
-        case MissingRef(ownerd, name) =>
-          if (generateStubs)
+        case m @ MissingRef(ownerd, name) =>
+          if (generateStubs) {
+            m.ex.printStackTrace()
             ctx.newStubSymbol(ownerd.symbol, name, source)
+          }
           else NoSymbol
         case NoDenotation | _: NoQualifyingRef =>
           throw new TypeError(s"None of the alternatives of $this satisfies required predicate")
@@ -858,7 +860,9 @@ object Denotations {
   /** An error denotation that provides more info about the missing reference.
    *  Produced by staticRef, consumed by requiredSymbol.
    */
-  case class MissingRef(val owner: SingleDenotation, name: Name)(implicit ctx: Context) extends ErrorDenotation
+  case class MissingRef(val owner: SingleDenotation, name: Name)(implicit ctx: Context) extends ErrorDenotation {
+    val ex: Exception = new Exception
+  }
 
   /** An error denotation that provides more info about alternatives
    *  that were found but that do not qualify.
diff --git a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
index af33ce3c2723..6e405d5f827b 100644
--- a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
+++ b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
@@ -405,6 +405,7 @@ class Scala2Unpickler(bytes: Array[Byte], classRoot: ClassDenotation, moduleClas
               // println(owner.info.decls.toList.map(_.debugString).mkString("\n  ")) // !!! DEBUG
               //              }
               // (5) Create a stub symbol to defer hard failure a little longer.
+              new Exception().printStackTrace()
               ctx.newStubSymbol(owner, name, source)
             }
           }